It can hit an neemy that is swapping out before the enemy swaps. For exmple, take the situation of Andromeda vs Phoebe. Phoebe chooses to swap. If Andromeda uses Rain of Arrows, Phoebe will get hit by the attack, then switch, but if Andromeda uses Trueshot, Phoebe will swap first, the attack will miss, and whoever Phoebe sapped for will take her place on the battlefield.
Try Cave of Trials 5 and fight the invisi-goblin. He does 9999999 damage to everyone and 1HKO's the castle. Try once with Athena and once without Athena.
Counters are easy just use hero, black knight or tauros and heal with the spell and the counter-wave will die. Destroying the castle also kills all the enemies.
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